I can't speak to vinegar syndrome, but I do know that nitrate film was insanely flammable. A few decades ago, a lot of old film that had not been catalogued completely yet was stored in an outbuilding at the George Eastman House in Rochester, where they specialize in preserving old film. In the middle of the winter, as I remember, the building caught fire from the inside and burned to the ground -- taking with it most of the two-reel Charlie Chaplins, a lot of the Buster Keatons, and some of the only copies of the first one-reelers and two-reelers from the first decade of the 1900s and before. What I remember is something about someone leaving a light on in the building, and the heat from that started the fire in the film; of course, I wasn't there so I can't say how it was stored.